Multi-anvil force compensating pressure apparatus



1962 e. GERARD ETAL 3,049,756

MULTI-ANVIL FORCE COMPENSATING PRESSURE APPARATUS Filed June 14, 1960INVENTORS. GEORGE GERARD 8 JACOB BRAYMAN 3 ATTORNEYS.

United States Patent Ufiice 3,549,756 Patented Aug. 21, 1962 3,049,756MULTI-ANVIL FORCE COMPENSATHNG PRESSURE APPARATUS George Gerard,Yonkers, and Jacob Brayman, Staten Island, N.Y., assignors toEngineering Supervision Company, New York, N.Y., a corporation of NewYork Filed June 14, 1960, Ser. No. 35,933 6 Claims. (Cl. 1816) Thisinvention relates to apparatus for producing high pressure on an object,and, more particularly, to apparatus of this sort wherein such highpressure is produced by a plurality of anvils acting on the ObjC'[. Thepresent application is a continuation-in-part of our copendingapplication Serial No. 833,809 filed August 13, 1959 and entitled,Pressure Apparatus. The apparatus disclosed in the present applicationis similar to that shown in FIG. 1 in our US. Patent 3,044,113 issuedJuly 17, 1962 in that a single pressing member is adapted by movementrelative to a reference datum to actuate all of a plurality ofpressure-multiplying anvils disposed in three dimensions around acentral cavity to compress an object in that cavity.

For a better understanding of the invention, reference is made to thefollowing description and to the accompanying drawings wherein:

FIG. 1 is a plan view of an embodiment of the invention in which theanvils slide in relation to a means which backs those anvils;

FIG. 2 is a front elevation, taken partly in cross-section, of the FIG.1 embodiment;

FIG. 3 is a View of a cross section in the vertical plane of one of theanvils of the FIG. 1 embodiment;

Referring now to FIG. 1, the numerals and 11 designate, respectively, asample to be compressed and a body of pyrophyllite which encloses thatsample, and which is in the form of a regular tetrahedron. The sample 10may be inserted in the pyrophyllite body 11 in the manner described byH. T. Hall in this article published at pages 267-275, volume 29 of TheReview of Scientific Instruments (1958). Thus, the sample may beinserted alone or may be contained within a metal cylinder (not shown)which in turn is inserted within the pyrophyllite body 11. If desired,electrical connections may be made to the cylinder by silver foil strips(not shown) which extend from the cylinder to the surface of thepyrophyllite body 11 to provide respective electrical terminals in theform of metal tabs lying fiat on the separate faces of such body.

The top of tetrahedral body 11 is contacted by an anvil 21 (FIG. 2). Aplurality of anvils 22, 23 and 24 are shown in FIG. 1 as contacting thethree downward facing sides of body 11.. The axes of the four anvilscoincide with the four axes of the tetrahedral body 11 which pass atright angles to the faces of such body and through the centers of suchfaces. The anvils 22 and 24 have substantially the same structure as theanvil 23 whose construction appears in detail in FIG. 3 to whichreference is now made.

The anvil 23 includes a hard end piece 25 which is made, say, ofcemented tungsten carbide, and which has a truncated front end providingthe anvil tip. The anvil also includes a bearing ring 26 and a pressuredisk 27, both made of steel. The end piece 25 is received with a hardpress fit within a forward bore of the bearing ring 26 which provideslateral support for the end piece. The pressure disk 27 is received witha close fit within a larger rearward bore of the bearing ring 26 to makecontact with the rear end of the hard end piece 25.

The hard end piece 25 of anvil 23 is chamfered at its front at 120intervals around its periphery to produce a diminishing taper formed bythree chamfer faces of which the faces 28, 29 and 29' are shown in FIG.3, the latter two faces being seen edgewise. This taper shapes the frontcontact face 30 of the end piece 25 to be in the form of an equilateraltriangle. The edges of this triangle are somewhat less in length thanthe edges of the equilateral triangle formed by the face of thepyrophyllite body 11 with which the face 30 of end piece 25 is broughtinto contact. For example, the face 34 of the end piece may measure /2on an edge, whereas the corresponding face of body 11 may measure 6" onan edge. The slanting chamfer planes formed in the front end of endpiece 25 are continued out to the cylindrical surface of the bearingring 26 by chamfering the front end of the bearing ring at intervals andwith the same inclination as the chamfers of the end piece.

The vertical anvil 21 is generally similar in construction to thepredominantly horizontal anvils 22-24. The upper or rear face of theVertical anvil is flat.

As shown by FIG. 2, the anvils 2224 are fitted within the interior of asleeve 50 so as to slide over such interior to be wedged inwardly bysuch sleeve when the entire anvil array is subjected to a compressiveload.

The wedging action of the sleeve is produced by having the sleeveinterior in the form of a conically tapered bore (whose Wall is inclined715 to the horizontal) and by having the rearward face of each of anvilsZZZ-24 shaped to match (i.e. be concentric with) the area of theconically tapered wall 181 of the bore which is opposite such rearwardface at, say, the time when the anvils of the array have been driveninwardly towards object 11 by the full amount for which the array isdesigned.

Small plastic (e.g., nylon) spacers in the form of buttons may beinserted in the gaps existing between the chamfered faces of the fouranvils which are employed. As so inserted, the spacers serve to hold theanvils in tetrahedral disposition prior to a pressing operation. Thespacers are of low compressive strength and, hence, are easily flattenedduring such operation.

The sleeve 50 is in the nature of a piston received with a tight slidingfit in the bottom of a cylindrical bore 185 formed in a housing 186.Such bore 185 contains therewithin a smaller diameter, concentric hub187 which projects upwardly from the bottom of the bore to be receivedwith a tight sliding fit in a cylindrical recess formed in the bottom ofthe cylindrical sleeve 58. As shown, the hub 187 provides a seat forsleeve 51 such that an annular clearance space 188 is produced betweenthe bottom of the bore and the bottom of the sleeve when the sleeve isat rest. To the end of moving the sleeve 51) within bore 185, the hub187 has formed therein a fluid conduit 189 which is coaxial with thehon-sing and hub, and which extends through the bottom of the housingand then through the hub to permit injection of hydraulic fluid behindthe sleeve. This hydraulic fluid is initially received in an axiallyshallow, cylindrical recess 190 of smaller diameter than hub 187 andformed in sleeve 50 to be directly above the outlet (at the top of thehub) of the hydraulic fluid conduit 189.

At its upper end, the sleeve 50 has formed therein a circumferentialannular recess into which is received an annular sealing ring 196 whichmay he, say, either of the O-ring or of the chevron packing type, andwhich is squeezed between sleeve 50 and the interior wall 197 of bore185 to provide a tight fluid seal. As will be noted, the sealing ring196 is disposed above the region at which the predominantly horizontalanvils 22 24 bear against the interior of sleeve 50. The reason for thislocation of the ring 196 will be later explained.

The bore 185 of housing 186 has a slight radial enlargement over thevertical interval thereof which extends from the top of the housing to apoint somewhat above the sleeve 50. The lower end of this radiallyenlarged section of bore 185 provides within the bore a shallow,circumferential annular seat 200 for the upper part of a reaction head201 for the vertical anvil 21. The lower part of such head is in theform of a downwardly projecting boss 202 of which the undersurafce is ahorizontal, planar bearing surface 203 against which the upper face ofvertical anvil 21 is adapted to abut with a flat contact. If desired,the anvil 21 may be made integral with the reaction head 201.

Between operations, the head 201 is removable from the bore 185 topermit insertion or manipulation therein of the anvil array. As apreliminary, however, to a pressing operation, the head 201 is locked inplace in the bore 185. To this end, the upper part of the mentioned borehas formed therein an annular, circumferential channel 210 having arectangular cross section and having, also, a bottom wall 211 which isvertically flush with the top surface 212 of reaction head 201 when thathead is resting on its annular seat 200. Into this recess 210. there areinserted a plurality of sector-shaped lugs 213 which are short enough inarc length to permit them to be turned to horizontal position within theupper part of bore 185. At the same time, the lugs 213 are large enoughin radial dimension to overlap the top 212 of head 201 even though thelugs have been fully inserted into the annular channel 210 so as to abutagainst the radially outward wall thereof. By virtue of so overlappingwith the head 201, the lugs 213 preclude upward movement thereof withinthe bore 185.

Assuming that the reaction head 201 has so been locked in place, theapparatus is operated by injecting hydraulic fluid under pressurethrough conduit 189 into the bore or cylinder 185 and behind the sleeve50 to drive such sleeve towards the reaction head. When the sleeve 50 isso driven, it tends to carry with it the anvils 2224 and the centralobject 11. Such object cannot, however, displace vertical anvil 21upwardly inasmuch as the vertical anvil is backed by the reaction head201. Hence, instead of the central object 11 moving upward, the head20]. exerts through anvil 21 on that object a progressively increasing,downwardly directed force. The effect of this downward force is toproduce a downward sliding of the rear faces of anvils 2224 overrespective portions of the conically tapered interior wall 181 of sleeve50 such as to cause those anvils to be wedged by such wall towardsobject 11 to render it simultaneously compressed by all four anvils.

To the end of permitting free sliding of the butt faces of anvils 2224over the slide surfaces respectively provided therefor by the conicallytapered inner wall 180 of sleeve 50, a bearing sheet (not shown) ofpolytetrafluoroethylene (for which the trademark is Teflon) may beinserted between each such butt end the slide surface by which the buttface is backed. A similar sheet of polytetrafinoroethylene may beinserted between the vertical anvil 21 and the bearing surface 203 bywhich the reaction head 201 drives that anvil. The mentioned plasticsheets have a twofold purpose. First, in the case of the sheets insertedbetween the anvils 2224 and their corresponding slide surfaces, suchsheets serve as an excellent lubricant between the rear faces of theanvils and the slide surfaces when those sheets are subjected to thehigh pressure which are produced in the described appathe slide surfacesin order to render sliding over those surfaces.

By continuing the advancement under pressure of sleeve 50 toward head201, the pressure on the tetrahedral pyrophyllite body 11 is intensifieduntil the body 11 and encased sample, have been compressed to thedesired degree, or until the capacity of the apparatus has been reached.During the compression, some of the pyrophyllite in the body 11 extrudesinto the interstices between the front faces of thefour anvils to form agasket. The remaining pyrophyllite becomes plastic or semi-plastic toact as an excellent transmitter throughout its mass of the pressureexerted thereon. Hence, the pyrophylli-te transmits the pressure fromthe anvils to the encased sample at a very high pressure value, as say,pressure on the order of 125,000 atrn. The anvils 2224 each exert on theinterior of sleeve 50 an outwardly directed force which progressivelyincreases in magnitude as the compressive loading of the anvil arrayincreases. Those outwardly directed forces produce in the sleeve thefollowing two effects. First, the restraint offered by the sleeve to themovement under those forces of anvils 2224 is a factor which results inthe development in the sleeve of internal stresses. Evidently, theconcentration of such stresses must be maintained sufliciently low atall points in the sleeve body to avoid rupturing of the sleeve by theloading impressed thereon from the anvil array.

Second, assuming that undue stress concentrations in the sleeve havebeen successfully avoided, nonetheless the loading of the sleeveproduces therein a deformation in the nature of an elastic expansion.Such expansion is undesirable since, in proportion to its amount, itdiminishes the wedging displacements of anvils 2224 towards the object11 to be compressed, whereby those displacements become less than thedisplacement towards that object of the vertical anvil 21. Because ofthis inequality of displacement, in the course of a compressingoperation the gaps. between adjacent lower anvils are rendered largerthan the gaps between such lower anvil and the vertical anvil 2-1. Itfollows that more pyrophyllite will be extruded from the object 11 intothe larger lower gaps than into the small upper gaps, and, accordingly,the central object will be subjected to an asymmetrical compressionwhich seriously reduces the efficiency of the pressing operation.

One way of dealing with the stressing and expansion of the sleeve is, ofcourse, to make the sleeve of suificient thickness to reduce toacceptable levels both the stress concentrations therein and the elasticdeformation thereof. At large tonnages, however, a sleeve of thenecessary thickness becomes cumbersome, expensive and largelyineffectual. Further, even at moderate loading tonnages a thick sleevehas a limit to its effectiveness in that the loading force on the sleeveis opposed only in a passive manner.

In the described embodiment, on the other hand, the loading on thesleeve is actively opposed by means as follows. When hydraulic fluid isinjected through conduit 89 into cylinder 185, some of this fluidmigrates from the shown recess 190 into the interspace 220 which isbounded at its upper end by the sealing ring 196 and, below this ring,by the interior and exterior walls of, respectively, the cylinder andthe sleeve 50. Because the interspace 220 is fluid sealed at its upperend by the ring 196, during the compressing operation the hydraulicfluid in such interspace is maintained at approximately the samepressure as that which urges the sleeve 50 upwardly in the hydrauliccylinder 185.

Now, in order to produce a progressive upward driving of the sleeve 50,over the duration of a compressing operation the pressure on thehydraulic fluid is progressively increased to thereby produce theheretofore described progressive increase in the outwardly directedforces exerted on the interior of the sleeve by the anvils 2224. In theinstance, however, of the FIGURE 12,

those anvils free 13 modification, because the sealing ring 196 isdisposed above the region where those anvils act on the interior of thesleeve, the pressurized fluid in the interspace 220 vertically extendsabove and surrounds such region. Hence, as the hydraulic fluid pressurebuilds up to produce the described progressive increase in the outwardlydirected forces acting on the interior of the sleeve, the sameincreasing hydraulic pressure acts in the interspace 220 at the level ofthose forces and against the exterior perimeter of the sleeve to exertthereon an inwardly directed force which is in line with those outwardlydirected forces and which actively opposes them. It follows that thementioned outwardly directed forces are at all times dynamicallycompensated for by the pressure of the hydraulic fluid.

The described compensating effect eliminates to a large degree theradial expansion of the retaining sleeve due to anvil loading. Suchreduction in the radial expansion of the sleeve produces, in turn, amore equal compression by all four anvils of the sample to be compressedand of its pyrophyllite jacket. Evidently, the counterbalancing of theforces exerted outwardly on the sleeve by the pressure exerted inwardlythereon permits the use of a sleeve which, for a given loading tonnage,may be considerably thinner, lighter, and less expensive than the sleevewhich would be required if no such counterbalancing were present.Further, such counterbalancing of the outwardly directed forces on thesleeve results in a substantial reduction in the stresses therein,particularly discontinuity stresses occurring at the junction of thevertical cylindrical wall of the sleeves and the bottom thereof. Stillfurther, it is to be noted that the described compensation of the sleevefor anvil loading may be obtained as an advantage which costs nothing interms of extra structure necessary to yield such advantage. This is soinasmuch as the sealing ring 196 and interspace 220 which provide thecompensation are conventional features of a hydraulic drive system, andinasmuch as a hydraulic drive system would commonly be used to actuatean anvil press of the sort described.

The above described modification being exemplary only, it will beunderstood that the invention herein comprehends apparatus differing inform and/or detail from that modification. For example, evidently, thesleeve need not have a conically tapered interior surface to the end ofwedging ones of the anvils towards the central object. Instead, suchanvils may be wedged by planar slide surfaces.

As another example, while the compensation of the anvil retaining sleevefor anvil loading has been specifically described herein in connectionwith the embodiment shown herein, each of the embodiments shown in ourapplication Serial No. 833,809 by FIGURES l to 3, by FIGURES 4 and 5, byFIGURES 6 and 7, by FIG- URES 8 and 9, and by FIGURES l0 and 11 is anembodiment which can likewise be modified to provide for similarcompensation of the sleeve thereof. Further, while in the embodimentshown herein the same hydraulic piston and cylinder combination providesthe means by which the anvil array is actuated and the means by whichthe sleeve is compensated for the loading exerted thereon by the anvilarray, the invention is also of application in instances where thepressurized hydraulic fluid which compensates the sleeve for anvilloading is separate from the means which actuate the anvils. Thus, forexample, the invention is of application in the instance where the anvilarray is actuated by the movement of a head, pressure plate or the liketowards a stationary sleeve surrounding ones of the anvils of the array,but where, as described herein, the stationary sleeve is surrounded byhydraulic fluid manifesting a pressure which increases in correspondencewith the increasing loading of the sleeve by the actuated anvil array.

Accordingly, the invention is not to be considered as 6 limited save asis constant with the scope of the following claims.

We claim:

1. Apparatus comprising, an array of anvils disposed to converge fromvarious sides on an object, a sleeve surrounding ones of said anvils andadapted at a region of contact with them to restrain them from outwardmovement, means adapted by loading said anvil array with a progressivelyincreasing force acting through said sleeve-surrounded anvils againstthe restraint provided by said sleeve to render said objectsimultaneously compressed by all the anvils in said array, afluid-containing housing surrounding the outer circumference of saidsleeve and mechanically separated from such circumference opposite saidregion of contact by a fluid-accommodating annular interspace, and meansto increasingly pressurize with hydraulic fluid said interspace betweensaid sleeve and housing to thereby exert on the outside of said sleevean inward pressure which increases in correspondence with said force toreduce deformation thereby of said sleeve.

2. Apparatus comprising, an array of anvils disposed to converge fromvarious sides on an object, a sleeve surrounding ones of said anvils andadapted to restrain them from outward movement, a hydraulic cylinder inwhich said sleeve is received as a piston, means to permit injection ofhydraulic fluid into said cylinder so as to produce movement therein ofsaid sleeve, means responsive to said movement to load said anvil arraywith a progressively increasing force acting through saidsleevesurrounding anvils against the restraint provided by said sleeveso as to render said object simultaneously compressed by all the anvilsin said array, and fluid sealing means surrounding said sleeve forwardof where said force acts thereon and adapted to retain pressurizedhydraulic fluid injected into said cylinder in the interspace bounded bysaid cylinder, sleeve and sealing means.

3. Apparatus comprising, an array of anvils disposed to converge fromvarious sides on an object, a sleeve surrounding ones of said anvils andadapted to restrain them from outward movement, a housing having formedtherein a hydraulic cylinder in which said sleeve is received as apiston, means to permit injection of hydraulic fluid into said cylinderso as to produce therein a movement of said sleeve which urges saidarray towards an end of said housing disposed forwardly of said array, astationary reaction head disposed within said housing at said endthereof to bear against said array when so urged, means adapted whensaid array bears against said head to load said anvil array with aprogressively increasing force acting through said sleeve surroundedanvils against the restraint of said sleeve, and fluid sealing meanssurrounding said sleeve forward of where said force acts thereon andadapted to retain pressurized hydraulic fluid injected into saidcylinder in the interspace bounded by said cylinder, sleeve and sealingmeans.

4. Apparatus as in claim 3 in which said reaction head is removable fromsaid housing, said apparatus further comprising head securing means tolock said head in place in said housing during said sleeve movement.

5. Apparatus comprising, an array of anvils disposed to converge fromvarious sides on an object, a sleeve surrounding ones of said anvils andadapted to rest-rain them from outward movement, a housing having formedtherein a hydraulic cylinder in which said sleeve is received as apiston to have the back end thereof mechanically separated by aninterspace from the part of said housing forming the rear wall of saidcylinder, means to increasingly pressurize with hydraulic fluid saidinterspace between said sleeve and housing so as to produce in saidcylinder a movement of said sleeve which urges said array towards an endof said housing disposed forwardly of said array, and a stationaryreaction head disposed within said housing at said forward end thereofto bear against said array when so urged so as to load said anvil aywith a progressively increasing force acting through said sleevesurrounded anvils restraint 'of said sleeve.

6. Apparatus comprising, a housing having formed therein a hydrauliccylinder open at one end and closed at the other, a piston received insaid cylinder to be separated from the circumferential wall thereof byan annular interspace surrounding said piston and adapted to be filledwith hydraulic fluid, said piston having formed therein a cavity openonly at the end of said piston towards the open end of said cylinder andadapted to contain an object to be compressed, means inserted in againstthe the open end of said cavity and adapted by relative motion with saidcavity to develop therein pressure on said object and also pressuredirected radially outwards on the circumferential bounding surface ofsaid cavity, and means to render the fluid in said interspacepressurized to exert on the circumference of said piston a pressuredirected radially inwards to oppose said pressure on said cavitybounding surface.

References Cited in the file of this patent UNITED STATES PATENTS2,125,068 Dempsey July 26, 1938 2,156,459 Mucher May 2, 1939 2,891,283Cramer et al. June 23, 1959 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 3,049,756 August 21, 1962 George Gerard et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 5 line 31 for "sleeves" read sleeve -5 column 6, line 31, for"surrounding" read surrounded Signed and sealed this 11th day ofDecember 1962 (SEAL) Attest:

ERNEST W SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents

